The Event-Related Potential Study On Cognition In Patients Of Depression

Depression is a series of mental disorder, which is caused by many reasons and is clinically characteristic of prominent and everlasting oppression which is not in accordance with the environments. Researches on depression have been the focus of the whole world for many years. The pathogenesis of such disease is so vague by now that the diagnosis of depression is parochial and subjective. So it comes to turn out a crucial problem that the accurate information will be provided for the clinical diagnosis and therapy estimation by detecting the cognitive functions. Fortunately the emergence and clinical appliance of the Event-Related Potential (ERP) supplies a technical platform to solve such matters.This study consists of three experiments: First, the difference of waveform of the contingent negative variation (CNV) was analyzed and compared between 10 depression patients and 17 normal subjects so as to assess the attention ability of the patients. Second, applying the novelty Oddball pattern, the ERP characteristics of selective attention of the 12 depression patients and 16 normal persons were investigated in order to determine whether the cognitive functions of the patients were influenced, such as involuntary attention and decision-making, etc. Third, the ERP waveform of the 12 patients and 16 normal subjects were analyzed when they attended the experiment of the facial recognition and the change of the special components of patients' facial recognition were observed to judge whether the patients have some deficiency in facial recognition ability.The main results of the study are as follows:1 .the results of the CNV pattern demonstrates that the depression patients needed longer time to respond to the signal than the normal group, and the A point's latency of the CNV was deferred, average amplitude lessened, so was the average amplitude of the late components of CNV. Our results was conform to the symptoms of the patients, such as the decline of the attention maintenance, diminishment of the expectant behaviors and the slow-down of the psychic motion response, which all demonstrated that the patients' attention maintaining ability decreased. Furthermore, the increase of the amplitude of P2 implied that the early processing of aesthesia required much more mental resources, it also indicated that when the patients completed their recognition, there was something wrong with the allotment and use of the mental resources, so was the processing of automatic cognition.2.The results of the novelty Oddball pattern demonstrated that the patients' group, compared with the normal group, apparently needed longer time to respond to the target stimuli, and had lower amplitude of the P3b in parietal lobe, P3a in frontal lobe and N2 in frontal lobe. What's more, the latency of P3b in patients' group was deferred apparently by contrast with that of the normal group. The delay of the P3b latency and the notable decrease in amplitude manifested the slow-down of the acceptance and processing of the information in the brain and the reduction of brain's resources, which was related to the sluggish thoughts, deficiency in the attentive initiative and depressive affections. The fall of the P3a amplitude in patients' group in frontal lobe reflected the decrease of the non-random attention, and the prominent diminishment of the N2 amplitude in frontal lobe, related to P300 closely, further suggested the deficiency of the frontal lobe's cognitive functions in the patients.3.The results of the facial recognition manifested that there were changes in the special components of the facial recognition in the group of the depression patients who had lower N170 amplitude in occipitalia and temporal lobes and higher VPP amplitude in the central part on the top than that of the normal group.